package 笔试记录.M9day11信锐;

import java.util.Scanner;

public class 青蛙跳台阶 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        System.out.println(solve(n));
    }

    public static int solve(int n){
        if(n < 3){
            return n;
        }
        int a = 1;
        int b = 2;
        int sum = 0;
        for (int i = 3; i < n; i++) {
            sum = (a + b) % 1000000007;
            a = b;
            b = sum;
        }
        return sum;
    }
}
